9,354 research outputs found

    Learning physics in context: a study of student learning about electricity and magnetism

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    This paper re-centres the discussion of student learning in physics to focus on context. In order to do so, a theoretically-motivated understanding of context is developed. Given a well-defined notion of context, data from a novel university class in electricity and magnetism are analyzed to demonstrate the central and inextricable role of context in student learning. This work sits within a broader effort to create and analyze environments which support student learning in the sciencesComment: 36 pages, 4 Figure

    Equilibrium orbit analysis in a free-electron laser with a coaxial wiggler

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    An analysis of single-electron orbits in combined coaxial wiggler and axial guide magnetic fields is presented. Solutions of the equations of motion are developed in a form convenient for computing orbital velocity components and trajectories in the radially dependent wiggler. Simple analytical solutions are obtained in the radially-uniform-wiggler approximation and a formula for the derivative of the axial velocity v∄v_{\|} with respect to Lorentz factor γ\gamma is derived. Results of numerical computations are presented and the characteristics of the equilibrium orbits are discussed. The third spatial harmonic of the coaxial wiggler field gives rise to group IIIIII orbits which are characterized by a strong negative mass regime.Comment: 13 pages, 9 figures, to appear in phys. rev.

    Contraction of the G_r,s Quantum Group to its Nonstandard analogue and corresponding Coloured Quantum Groups

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    The quantum group G_r,s provides a realisation of the two parameter quantum GL_p,q(2) which is known to be related to the two parameter nonstandard GL_hh'(2) group via a contraction method. We apply the contraction procedure to G_r,s and obtain a new Jordanian quantum group G_m,k. Furthermore, we provide a realisation of GL_h,h'(2) in terms of G_m,k. The contraction procedure is then extended to the coloured quantum group GL_r{\lambda,\mu}(2) to yield a new Jordanian quantum group GL_m{\lambda,\mu}(2). Both G_r,s and G_m,k are then generalised to their coloured versions which inturn provide similar realisations of GL_r{\lambda,\mu}(2) and GL_m{\lambda,\mu}(2).Comment: 22 pages LaTeX, to be published in J. Math. Phy

    Origin and Suppression of 1/f1/f Magnetic Flux Noise

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    Magnetic flux noise is a dominant source of dephasing and energy relaxation in superconducting qubits. The noise power spectral density varies with frequency as 1/fα1/f^\alpha with α∌1\alpha \sim 1 and spans 13 orders of magnitude. Recent work indicates that the noise is from unpaired magnetic defects on the surfaces of the superconducting devices. Here, we demonstrate that adsorbed molecular O2_2 is the dominant contributor to magnetism in superconducting thin films. We show that this magnetism can be suppressed by appropriate surface treatment or improvement in the sample vacuum environment. We observe a suppression of static spin susceptibility by more than an order of magnitude and a suppression of 1/f1/f magnetic flux noise power spectral density by more than a factor of 5. These advances open the door to realization of superconducting qubits with improved quantum coherence.Comment: Main text: 5 pages, 4 figures. Supplement: 8 pages, 6 figure

    Seismic velocity structure of seaward-dipping reflectors on the South American continental margin

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    Seaward dipping reflectors (SDRs) are a key feature within the continent to ocean transition zone of volcanic passive margins. Here we conduct an automated pre-stack depth-migration imaging analysis of commercial seismic data from the volcanic margins of South America. The method used an isotropic, ray-based approach of iterative velocity model building based on the travel time inversion of residual pre-stack depth migration move-out. We find two distinct seismic velocity patterns within the SDRs. While both types show a general increase in velocity with depth consistent with expected compaction and alteration/metamorphic trends, those SDRs that lie within faulted half grabens also have high velocity zones at their down-dip ends. The velocity anomalies are generally concordant with the reflectivity and so we attribute them to the presence of dolerite sills that were injected into the lava pile. The sills therefore result from late-stage melt delivery along the large landward-dipping faults that bound them. In contrast the more outboard SDRs show no velocity anomalies, are more uniform spatially and have unfaulted basal contacts. Our observations imply that the SDRs document a major change in rift architecture, with magmatism linked with early extension and faulting of the upper brittle crust transitioning into more organised, dike-fed eruptions similar to seafloor spreading

    Mentoring during surgical training: Consensus recommendations for mentoring programmes from the Association of Surgeons in Training

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    AbstractMentoring has been present within surgical training for many years, albeit in different forms. There is evidence that formal mentoring can improve patient outcomes and facilitate learning and personal growth in the mentee. The Association of Surgeons in Training (ASiT) is an independent educational charity working to promote excellence in surgical training. This document recommends the introduction of a structured mentoring programme, which is readily accessible to all surgical trainees.A review of the available evidence – including an ASiT-led survey of its membership – highlights the desire of surgical trainees to have a mentor, whilst the majority do not have access to one. There is also limited training for those in mentoring roles. In response, ASiT have implemented a pilot mentoring scheme, with surgical trainees acting both as mentors and mentees. Based on the existing literature, survey data and pilot experience, ASiT formalises in this document consensus recommendations for mentoring in surgical training

    The Integration of Lean and Human Resource Management Practices as an Enabler for Lean Deployment- A Systematic Literature Review

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    Purpose – The current research aims to map and investigate how Human Resource Management and Lean practices can be integrated. This investigation will help identify the Human Resource Management aspects critical in the success of Lean initiatives while exploring the research gaps in the existing literature. The review also aims to delineate the benefits and challenges of integrating Lean with Human Resource Management systems to discuss further research and practice areas. Design/methodology/approach – This study utilizes a Systematic Literature Review method to identify and synthesize the existing literature. As part of the process, a protocol that provided a plan for the review was followed, including the research questions and the data to be extracted. Findings– The study results indicate that aspects of Human Resources Management practice and policies such as Training & Development, Teamwork, Motivation, Communication, Leadership, are key enablers of Lean initiative deployment and success. The benefits of the integration of Human Resources with Lean 15 can help in Lean training and development, communication of Lean initiatives and successes, allocating and hiring continuous improvement personnel, and supporting leadership in Lean deployment. Challenges to integrating Lean and HRM practices included lack of integration and collaboration between disciplines. Further exploration areas in successful Lean deployment would be practical longitudinal case studies on Lean deployments with HR partnerships and involvement. Practical implications – This review paper has crucial implications for practice relating to, integration of Lean with Human resource management structures and tailoring Human resource management initiatives to ensure the success of Lean deployment and reduce risks of failure. Originality/value – The Systematic literature review study conducted in this paper is the first of its kind to integrate and map the human resource management concepts that can be integrated with Lean to deploy the initiative successfully. This mapping is critical for ensuring the success of Lean methodologies within an organization and paves the way for future research. In addition, managers and organizations can find support and guidance from this study to focus on vital areas of partnership between their Lean and HR programs
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